The increasing popularity of elaborate Quality-of-Service (QoS) frameworks such as Integrated Services and Differentiated Services puts emphasis on packet schedulers that allow flexible bandwidth management. Because of the heavy implementation cost of packet schedulers that feature optimal delay performance and because worst-case delay performance is actually rather secondary to robust bandwidth performance in IP networks, the industry is showing strong interest in Weighted Round Robin (WRR) schedulers [see references 1, 2, 3 listed in the attached Appendix], which have very low complexity and can provide robust bandwidth guarantees and fairness, but do not necessarily achieve tight delay bounds. A WRR scheduler can provide strict bandwidth guarantees to guaranteed-bandwidth (GB) flows (i.e., flows with specified bandwidth requirements) and service fairness to best-effort flows (i.e., flows with no specified bandwidth requirements) when it handles flows of either type in isolation (i.e., without flows of the other type). Typically, the aggregation of GB and BE flows in a single WRR scheduler compromises the efficiency of the server in allocating bandwidth resources. In existing WRR schedulers, a BE flow can be serviced only if it is allocated a service share. The selection of the service share is always arbitrary, and intrinsically compromises the flexibility that should instead characterize the distribution of bandwidth to BE flows. Furthermore, the service shares allocated to the BE flows are subtracted from a bandwidth pool that is shared with the GB flows, which implies a reduction in the amount of GB flows that the scheduler can support.
What is desired is an improved WRR scheduler that can efficiently integrate GB and BE flows.